A voltage regulator or load tap changer utilizes a tap changer that employs a secondary circuit detector to actuate a mechanical linkage that selectively engages taps of a tapped section of winding to maintain a substantially constant voltage on an output of the regulator in response to voltage variations on an input of the regulator. Arcing occurs during changes in the tap position, which results in some erosion of involved contacts. This contact erosion continues until maintenance is performed on the tap changer and the contacts are replaced, or until the contacts erode to a point where the contacts no longer make electrical contact with one another, resulting in an electrical outage. As a result, remaining contact life impacts maintenance schedules and service reliability of the voltage regulator.
A separate phenomenon, known as coking, may occur if the tap changer contacts stay on a particular position for an extended period of time. Coking refers to carbon deposits that form on the tap changer contacts. These deposits shorten contact life and may lead to a premature service interruption. Preventing coking from occurring requires that the tap changer contacts be moved, or ‘wiped,’ periodically. To prevent coking, the tap changer may be tapped to wipe the carbon deposits from the contacts.